Ground probing radar systems have been used for many years to investigate subsurface conditions of the earth's crust and to locate buried objects and the like. A typical ground probing radar system according to the prior art includes an antenna system, a pulse generator for supplying transmit pulses to the antenna system and a receiver for receiving the returned radar signal impinging on the antenna system and for converting the received signal into a useful image.
The conversion of the received signal into a useful image can be a complicated process. Typically, a variety of signal processing operations may be applied to the received signal to remove noise from the signal, to distinguish the useful information from unwanted information, and so forth. This processing frequently applies to the received signal a gain function which varies with time and, correspondingly, with the instantaneous depth of the scattering or reflective media which returned the received echo.
As with all radar systems, the performance of ground probing radar systems depends on many factors. One of the more important factors, as suggested above, is the antenna system employed. Antenna pattern, aperture, gain and other factors affect the amount of power needed, the depth to which the ground can be probed, the detection sensitivity, the focus of the received image, and so forth. For these reasons, there is no such thing as one ideal antenna. Users have, in the past, sometimes desired to switch antennas from time to time in order to take advantage of, or get away from, the particular characteristics of one or more of the available antennas. For example, the user may notice in the image produced using a first antenna, a feature he or she would like to examine more closely using a second antenna. Since, as stated above, the antenna performance and the signal filtering are closely related, when an antenna is changed it is also necessary, generally, to change the received signal filtering. This might involve anything from a physical hardware change (i.e.., removing and inserting filter modules), to changing switch or control settings. In any event, time is required for disconnecting one antenna, connecting another antenna, and establishing the new filter conditions; even if no more than one switch need be reset, the filters will need some time to settle.
Accordingly, there exists a need for a radar system, particularly a ground probing radar system, which provides the capability to attach and rapidly switch between a plurality of antennas.